Percent Composition Calculator

The percent composition calculator is a handy tool in chemistry that determines the relative abundance of each element in a compound.

It expresses this as a percentage of the compound’s total mass. This calculator simplifies complex calculations, providing quick and accurate results for various chemical analyses.

For instance, consider water (H₂O). A percent composition calculator would reveal that it consists of approximately 11.19% hydrogen and 88.81% oxygen by mass.

Compound	Element	Mass (g)	Total Mass (g)	Percent Composition
H₂O	H	2.02	18.02	11.19%
H₂O	O	16.00	18.02	88.81%
CO₂	C	12.01	44.01	27.29%
CO₂	O	32.00	44.01	72.71%
NH₃	N	14.01	17.04	82.22%
NH₃	H	3.03	17.04	17.78%

Percent Composition Formula

For any element in a compound, it’s expressed as:

% Composition = (Mass of element / Total mass of compound) × 100

Let’s apply this to calcium carbonate (CaCO₃):

Calculate the molar mass: Ca (40.08 g/mol) + C (12.01 g/mol) + 3 × O (15.99 g/mol) = 100.07 g/mol

For calcium: % Ca = (40.08 g / 100.07 g) × 100 = 40.05%

For carbon: % C = (12.01 g / 100.07 g) × 100 = 12.00%

For oxygen: % O = (3 × 15.99 g / 100.07 g) × 100 = 47.95%

How do you find the composition of a percentage?

To determine the percentage composition:

Identify the compound’s chemical formula.
Calculate the molar mass of the compound.
Determine the mass of each element.
Apply the percent composition formula for each element.

Find the percentage composition of sulfuric acid (H₂SO₄)

Molar mass: 2(1.01) + 32.07 + 4(16.00) = 98.09 g/mol

Mass of H: 2.02 g
Mass of S: 32.07 g
Mass of O: 64.00 g

% H = (2.02 / 98.09) × 100 = 2.06%
% S = (32.07 / 98.09) × 100 = 32.69%
% O = (64.00 / 98.09) × 100 = 65.25%

What is the percent composition of H in C₁₀H₂₀?

To calculate the percent composition of hydrogen in C₁₀H₂₀:

Molar mass of C₁₀H₂₀: 10(12.01) + 20(1.01) = 140.30 g/mol
Mass of H: 20 × 1.01 = 20.20 g
% H = (20.20 / 140.30) × 100 = 14.40%

Thus, hydrogen constitutes 14.40% of C₁₀H₂₀ by mass.

What is the percentage composition of Na?

For sodium (Na), being an element rather than a compound, the percent composition is always 100%.

Molar mass of NaCl: 22.99 + 35.45 = 58.44 g/mol

% Na = (22.99 / 58.44) × 100 = 39.34%

Sodium comprises 39.34% of the mass in table salt (NaCl).

How do you find grams from percent composition?

To determine the mass of an element from percent composition.

We know S is 32.69% of H₂SO₄.

32.69% = 0.3269

Grams of S = 0.3269 × 250 g = 81.73 g

81.73 g of sulfur are present in 250 g of sulfuric acid.

Sources / Reference URLs

Related Tools:

Percent Composition Calculator – Calculating Elemental Composition